RavenMocker

I have access to an adapter plate with gear that mates a Chevy TH400 and the Dana 20.

What about a Dana 20 behind an TH400?

I could go with a TH400 and then swap over at a later date when I am better set up for it fundage wise.

If I go the 4L80E route then I need to run either a controller or set it up to run manually. I think a 700R4 would work better. I will look into the axles and the NP205.

Maybe a mild lift using an OLD MAN EMU heavy duty suspension lift. Ive used OME and its an awesome setup. The heavy duty springs stiffen up the suspension for hauling stuff but gives an awesome ride.

You have a few choices. -- Coil addons for the shocks are a patch and really don't add any lift. -- If you have a spring shop in your area they can cut you an add a leaf or what ever springs you want for a decent price. <--- Ive gone this route on other rigs and was pleased. -- Air bag helpers. Look on craigslist as I see them at times of cheap. -- Customize your own spring packs using springs from other trucks. -- Overload springs. I don't like this option because most of them bind up the leaf springs to much. Ive also witnessed bent springs because of them as well as broken or damaged leafs from clamping them on to tight. You can buy new pins that are stronger and have a longer head. I would speak with a custom spring shop and see what they have to say as well. They know springs because its all they do and the shop can tell you what leafs to replace and make them for you as well as sale you the new pins.

Ive read up on a lot of different ways to do this but now I just want to hear what others have to say. I am converting my MJ to a Cummins 6AT 3.4. I am going to tune the engine to get the nearest I can on both power and fuel economy. But I can't decide what transfer case to go with. So I would be looking in the neighborhood of 140-175 hp and 250-300 lb-ft. My build thread has more basics about the engine being used. I like the idea of having AWD but if I am able to shift into a 2x4 mod that would be nice. I'm still figuring out what transmission to use, maybe an NV3500-4500 or a hybrid Jeep/Toyota transmission and tease. The Cummins has a chevy bell housing on it. Also I had thought I would need to covert to a front axle with the pumpkin on the passengers side between the turbo and exhaust are on the drivers side. But if I have the room I might pipe it under the engine like it currently is on the stock motor. Just don't know how a three inch pipe is going to fit. So I could use some advice on what way to go here. The biggest tire I intend to use would be a 33" but I liked using 235/85R16's and might just stay with those. The cummins fits in the engine bay so I won't need to worry about clearances as you would with a 6BT. The truck is intended as a daily driver, weekend warrior, lite towing and hauling stuff.

Is there anything special that I should keep from cutting up and modifying on the interior of my 1986 MJ? I mean its just the basic interior with a bench seat. I will be going to bucket seats and also wanted to modify the gauges to my own needs. Such as a tach for the cummins L6 I will be installing. I thought about taking out the stock instrument cluster and modifying it with other gauges and faces to match and try to make it look stock. But I was not certain if that instrument cluster was only in the MJ's. Anyway I just don't want to destroy something that might be hard to find that someone else might need.

Thanks thats helpful. I can't do anything yet until I get the engine pulled. And thats being a bit of a pain as I need to move the body someone else as I only have a single car garage down here and I live in a condo so I'm not allowed to park anything outside that doesn't run and is drivable. Right now I am thinking I might go with FZJ80 axles front and rear with oem electric lockers. I'm still going to a front leaf spring conversion and moving the transfer case to the passengers side, hence the front land cruiser axle. Ive also thought about transplanting the entire MJ only another truck frame thats already setup for the time being. Allowing me to drive it now and set up an actual proper conversion this summer. Are there any write ups on someone that has placed an MJ or XJ on a heavy duty truck frame?

The exhaust lets out on the drivers side of the engine bay. That is where the turbo is as well. So I may need to convert over to a passengers side pumpkin. If I do that then I am also going to consider beefing up the front frame and converting to front leaf springs.

I am also thinking about maybe using an automatic transmission this time around. Like a 700R4. I did however read up on using the AW4 and its Toyota counterpart in a Cummins 4BT application. Id rather like to stay away from computers and most electronics.

I'm currently getting around 20mpg city and mid twenties highway. If you want something that is going to give you great fuel economy I would go with a VW 1.9 TDI or even a 1.9 TD as there is not an ecm. They are lite and easily tunable. I will be cleaning this motor up and tuning it for better fuel economy rather then power.

Ive read his build and I liked how he went about it. This was already in my current truck before the guy placed one in his ford. Actually have several years and miles on this conversion and it always starts and never misses a beat. :)

I bought this MJ for a Cummins project. I have no intention on using the 4BT nor the much heavier 6BT. Rather I own an engine that isn't very well known. But more about the engine later. First about the truck. It is an 1986 Comanche 2.5 with an AX5, D30, and D35. The transmission is shot as is the engine. The front axle has seen better days as well. The interior is red and I really hate red interior so that is going to change to maybe a grey one. It has the bench seat, the headliner has been stripped out, and hardly any of the lights work on the dash. The doors have grey panels with hand cranks for the windows. The bed has dents and some deep scratches in places. Body has broken plastic here and there, I would have to say that the truck as it sits now has seen better days and was begging me (or anyone else that cared about it) to buy it and bring her back to life. So that is what I will do. Now for the engine. The engine is a Cummins 6-AT 3.4 liter turbo diesel. It is about the same size and weight of the AMC 6. Fully dressed it weighs in at about 680 pounds. Now do not let the size fool you. I have this motor in a 4000 pound 4x4 vehicle now. It tows and runs just fine and I have yet to tune it for more power. Now being the engine is about the same size as the AMC 6 or a Chevy 235cid, or a Landcruiser 2F, it should fit within the engine bay with no issues. The oil pan is a rear sump and I am certain it will have no clearance problems. If it is does then I will just modify the oil pan for the application. The engine uses a universal GM bell housing bolt pattern. The Transmission I want to use is still up in the air. I have thought about using either an SM465, NV4500, or even an NV3500. But I am open to ideas. The Transfercase is also not decided. Something that would compliment the transmission as well as allow me to continue to use the factory shifter because well I kinda like the way it works. I will not be keeping the CAD system. That is going bye bye. The Axles.... Might stay with the OEM front axle and eliminate all the CAD crap and lock it into place so I don't have to worry about that system ever giving me issues. Extra stuff just means something else that I have to worry about breaking and/or troubleshooting. If it isn't on the truck, I don't have to worry about it. The D35 is getting dumped for something stronger. I might use an Aussie locker in the rear but also considering an ARB locker. Also would like to have 4 wheel disc brakes.

It also has the D35 rear axle and the crappy 5speed transmission. So all around its a dog. But not for very much longer. As soon as I get my garage cleared out then the fun begins. Cummins 6 AT 3.4 turbo diesel. :) Just have to decide which transmission to go with and what tcase.

Thanks everyone. I will start my build thread soon.

Hi everyone. I just purchased my first MJ for 500. Ive owned a few XJ's over the years but have yet to buy an MJ. This one is an 1986 MJ with the AMC 4 and 5 speed. Has a blown fourth gear and needs lots of work. Valve guides are shot, front axle leaks, and there are vacuum lines all over the place Ive no idea where they go. Also have no idea where the vacuum line goes for the front axle as it is just hanging there unplugged.